1. Technical Field
The present invention generally relates to processes for making overbased, sulfurized salts of alkylated hydroxyaromatic compounds.
2. Description of the Related Art
Medium to long chain alkyl aromatics are used to make high volume additives and surfactants. Examples of such compounds are alkyl aromatic phenates used in lubricant additives. Phenates are widely used for their detergency and antioxidant properties.
Low molecular weight alkylphenols such as tetrapropenyl phenol (TPP) have been used as a raw material by producers of sulfurized, overbased phenates. When sulfurized, overbased phenates are made generally there is unreacted alkylphenol in the final reaction product. A recent reproductive toxicity study in rats sponsored by the Petroleum Additives Panel of the American Chemistry Counsel shows that in high concentrations unreacted TPP may cause adverse effects in males and female reproductive organs.
To reduce any potential health risks to customers and avoid potential regulatory issues there is a need to reduce the amount of unreacted low molecular weight alkyl hydroxyaromatic compounds in overbased, sulfurized salts of alkylated hydroxyaromatic compounds. Linear olefins are a possible alternative to avoid reproxicity in the derived alkylphenols; however, the linearity of the olefin can lead to poor low temperature properties in lubricating oils containing the derived sulfurized, overbased phenates.
U.S. Pat. No. 5,318,710 discloses a Group II metal overbased sulfurized alkylphenol composition derived from an alkylphenol enriched of a formula wherein the alkyl substituent of the phenol is a straight chain.
U.S. Pat. No. 5,320,762 discloses a Group II metal overbased sulfurized alkylphenate composition derived from an alkylphenol enriched in substantially straight chained alkyls.
U.S. Pat. No. 6,670,513 (“the '513 patent”) discloses a process for producing an alkylated, hydroxyl-containing aromatic compound. The '513 patent further discloses that the process involves (a) isomerizing a normal alpha-olefin or mixture of normal alpha-olefins having from about 16 to about 30 carbon atoms in the presence of a first acidic catalyst capable of inducing both olefin isomerization and skeletal isomerization to produce a mixture of isomerized olefins; and (b) alkylating a hydroxyl-containing aromatic compound with said mixture of isomerized olefins in the presence of a second acidic catalyst comprising a sulfonic acid resin catalyst or an acidic clay.
U.S. Patent Application Publication No. 20020091069 discloses an additive produced by a process comprising: (a) isomerizing an olefin using an iron pentacarbonyl catalyst to produce an isomerized olefin; (b) alkylating an oxy benzene with the isomerized olefin to produce an alkyl oxy benzene, wherein the oxy is selected from the group consisting of hydroxy, methoxy, ethoxy, propoxy, butoxy, pentoxy, and hexoxy; (c) sulfonating the alkyl oxy benzene to produce an alkyl oxy benzene sulfonic acid; and (d) overbasing the alkyl oxy benzene sulfonic acid to produce an overbased, alkyl oxy benzene sulfonate having a TBN of at least 200.
It is desirable to provide improved processes for making overbased, sulfurized salts of alkylated hydroxyaromatic compounds.